Chromatography is a well-established and valuable technique for separating chemical and biological substances and is widely used in research and industry, finding many applications in compound preparation, purification and analysis. There are many different forms of chromatography, liquid chromatography being of particular importance in the pharmaceutical and biological industries for the preparation, purification and analysis of proteins, peptides and nucleic acids.
Columns used in liquid chromatography typically comprise a tubular body enclosing a porous chromatography medium through which a carrier liquid flows, with separation taking place by material collection between the carrier liquid and solid phase of the porous medium. Prior to any separation process, the bed has to be prepared starting from the slurry of particles that has to be introduced into the column. The packed bed is formed by consolidating a suspension of discrete particles, known as “slurry” that is pumped or poured or sucked into the column, usually from one end. The end piece or net allows liquid to flow from the column whilst retaining the porous material and consolidates the particle from the slurry inside the column.
The size of columns varies depending upon the scale of separation which is required. Thus, for example, research laboratories may only require columns which hold relatively small volumes of chromatography media, typically of the order of 100 μl to 1 L. In contrast, industrial laboratories which handle high volumes of samples which require purification or preparation, often require columns with much greater capacities, typically well in excess of 5 L and often in the 50 L to 1000 L range.
There are many different forms of chromatographic media used for separating, purifying and analysing chemicals such as proteins, peptides and nucleic acids. For example, some media effect separation on the basis of size while others utilise charge and/or affinity to separate the analyte of interest.
Chromatographic media which is to be used for packing industrial columns is often stored and transported in large containers to industrial laboratories. These containers, which can be made of any suitable inert material such as plastic or metal, typically hold in excess of 5 L of chromatography media and are heavy and difficult to manipulate, particularly the larger containers which hold 50 L-100 L of media. Due to their bulk and weight, the containers are generally transported from suppliers to industrial laboratories on pallets to facilitate mechanical handling. In order to prevent or minimise microbiological contamination, the media is often stored in an alcoholic or bacteriostatic solution until such time as it is to be used for packing columns. The media tends to settle out on storage such that it is covered by a supernatant of the alcoholic or bacteriostatic solution.
Once the container reaches the industrial laboratory, it may be kept in storage until such time as the media is required for packing chromatography columns. In order to use the media for packing such columns, the supernatant is usually removed by siphoning or decanting as the alcoholic supernatant would impinge on both environmental and safety concerns in the laboratory facility. A suitable buffer or water is added to the container to make up the volume of storage solution removed and is then used to re-suspend the media. A homogeneous mixture of the re-suspended media is then produced by either manually shaking the containers, stirring them with a paddle or physically removing them from the carrier, such as a pallet, and manually rolling them across the floor. The resulting media must then be decanted or siphoned from these containers to another vessel for subsequent mixing with an appropriate concentration of a suitable buffer prior to packing the chromatography column.
Many problems are encountered in the above described process which are predominantly due to the size and weight of the containers. Decanting the supernatant manually from the containers can lead to a loss of expensive media. The preparation of an homogeneous mixture of media in the container by manually shaking or rolling the container is a time consuming and arduous task which requires considerable strength and dexterity of the operator. This procedure can pose safety risks to the operator in removing the heavy containers from the pallet to roll them in order to mix the media this is also a time consuming process. The mixed media must be continuously agitated or stirred in order to prevent it settling out on standing. Furthermore, problems also arise in transferring the media to a second vessel to form a final slurry for packing the column because media may be lost in siphoning or decanting it from the drum due to adhesion to the walls of the container or spillage. Additional problems may be encountered in diluting the media to a predetermined concentration (typically greater than 50% weight/volume) for use in packing a chromatography column.
The present invention addresses the aforementioned problems and presents methods, apparatus and systems for overcoming and resolving these technical difficulties. It is an object of the invention to provide an improved and more efficient method for forming a homogeneous mixture of chromatography media of all types in most typical containers and for transferring the mixture to a second vessel, such as a slurry tank, or to a chromatography column for packing. A further object of the invention is to provide apparatus and systems with which to carry out the improved method of the invention.